You have to defend the earth from strange viruses and particles. To do this, you fly out into space to shoot all the crazy viruses that can bring harm to earth. You control a spaceship. You cannot move the ship, but you can use it to shoot invaders and attackers. Move the mouse around your ship to rotate it and change where it is aiming. To fire, click in the direction to shoot all of the enemies in that direction. Try to clear the screen, otherwise they will attack your ship and your ships defense will fail. Each level will tell you how many waves of attackers there are that you have to defeat.